Like two solar thermal plants approved in the past week by California and federal regulators that will be built by SolarReserve, the Solana project will store the sun’s energy in molten salt. The heat can be released at night to create steam to drive an electricity-generating industrial turbine.

But the two companies are making bets on two different solar thermal technologies. Abengoa is relying on time-tested solar troughs in which long arrays of parabolic mirrors focus the sun on tubes of synthetic oil. The resulting heat is used to create steam that runs a turbine. Some of that heat will be transferred to salt-filled storage tanks that will allow Solana to operate up to six hours after sunset.

SolarReserve, on the other hand, will focus huge arrays of individual mirrors called heliostats on a 538-foot tower topped with a 100-foot receiver filled with thousands of gallons of molten salt. The salt will produce heat to create steam during the power plant’s daytime operation as well as for up to eight hours at night. The company, based in Santa Monica, Calif., says it will be able to produce hotter steam than a parabolic trough plant, allowing its projects to operate more efficiently.

Solar thermal projects that can produce electricity at night or when the sun is not shining appeal to utilities as they could reduce the need for expensive fossil-fuel power plants. In California, such power plants will be subject to greenhouse gas emissions caps beginning in 2012.

Abengoa will build the Solana project on farmland in Gila Bend, Ariz., about 70 miles southwest of Phoenix. The company has signed a 30-year power purchase agreement with utility Arizona Public Service.

The project is expected to create as many as 1,700 construction jobs and 180 jobs in a factory being built to supply the 900,000 mirrors to be deployed at Solana as well as equipment for Abengoa’s power plant projects in California.